Icky Bugs with my Gerbils! HELP!

I found one crawling up the tank today, it's small (pin head size) and maroon - except in the light, I caught one under the lamp and it looked scarlet - and are round.

Does anyone have any idea as to what they might be (lice, mites, ticks?) and how to get rid of them?

Thanks so much. Found out. So for anyone else who's having the same problem (apparently it's getting common with gerbils) they're avian mites. I have no idea why gerbils get them. Oh well...